The complexities of the triangular relationship between employer, worker and agency are explored in two sectors to establish the extent to which the use of agency workers constitutes strategic and rational decisions on the part of employers. Evidence of strategic subcontracting to agencies is evident in the ICT examples, but, as in the healthcare case, organizational outcomes need to be understood with reference to workers’ preferences, the agencies’ own sophisticated strategies, operational pressures and labour market context. Relationships with agencies were embedded but inherently contingent, reflecting their own dependency on clients or, in the case of healthcare, government.